title: L1cam acts as a modifier gene for members of the endothelin signalling pathway during enteric nervous system development.
abstract: BACKGROUND
  The enteric nervous system originates from neural crest cells that migrate into the embryonic foregut and then sequentially colonize the midgut and hindgut. Defects in neural crest migration result in regions of the gut that lack enteric ganglia, a condition in humans called Hirschsprung's disease. The high degree of phenotypic variability reported in Hirschsprung's disease suggests the involvement of modifier genes.
  
  
  METHODS
  We used a two-locus complementation approach to screen for genetic interactions between L1cam and members of the endothelin signalling pathway. Immunohistochemistry was used to label PGP9.5(+) enteric neurons and Sox10(+) neural crest-derived cells in wholemount preparations of embryonic gut. Key Results  Loss or haploinsufficiency of L1cam significantly increased the severity of aganglionosis in Et-3 and Ednrb null mutant embryos. Furthermore, the colonization of the developing gut by neural crest-derived cells was significantly delayed in L1cam(-/y) ; Et-3(-/-) and L1cam(-/y) ;Ednrb(sl/sl) embryos.
  
  
  CONCLUSIONS
  We have identified the X-linked gene, L1cam, as the first modifier gene for members of the endothelin signalling pathway during development of the enteric nervous system. Mutations in L1CAM may act to modulate the severity of aganglionosis in some cases of Hirschsprung's disease.
authors.affiliation: Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Melbourne, Victoria, Australia.
authors.forename: A S
authors.initials: AS
authors.lastname: Wallace
authors.forename: M X
authors.initials: MX
authors.lastname: Tan
authors.forename: M
authors.initials: M
authors.lastname: Schachner
authors.forename: R B
authors.initials: RB
authors.lastname: Anderson
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation; D016232:Endothelins / Q000235:genetics / Q000378:metabolism*; D017615:Enteric Nervous System / Q000002:abnormalities / Q000196:embryology*; D060045:Genes, Modifier; D050172:Genes, X-Linked; D005816:Genetic Complementation Test; D006627:Hirschsprung Disease / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007422:Intestines / Q000196:embryology / Q000294:innervation; D051379:Mice; D018345:Mice, Knockout; D039842:Neural Cell Adhesion Molecule L1 / Q000235:genetics* / Q000378:metabolism; D017466:Receptors, Endothelin / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D016232:Endothelins; D039842:Neural Cell Adhesion Molecule L1; D017466:Receptors, Endothelin